Mechanical devices are known for a long time, which mechanical devices are called slides for adjusting the longitudinal position of a seat in a vehicle, and in particular in an automobile vehicle.
Each slide is more often formed by a first profile member having a substantially U-shaped section which is upwardly open and secured onto the floor of the vehicle while a second profile member has a cross-section which is also substantially of a U-shape but open downwardly. The second profile member is placed in opposition to the first profile member, with sliding or rolling members being interposed between the first and second profile members for enabling the outer profile member to slide on the inner profile member. Moreover, the outer profile member is connected by suitable means to the seat of the corresponding vehicle, in order to allow a longitudinal adjustement of this seat according to morphology of the user.
Such slides are described and shown in particular in French patent 2,390,625; French patent 2,098,852; French patent 2,286,723; German patent 2,545,763; as well as in French patent 2,282,349.
However, these slides have not been found satisfactory since it has not been possible, up to know, to meet requirements which are often contradictory and which can be summarized as follows:
a) a sliding force which should be the smallest as possible despite geometrical defects of the vehicle floor, which sliding force is the force which is necessary for moving one profile member relatively to the other; PA1 b) these slides must be noiseless and must have, if possible, only a small clearance or even no clearance at all in order to improve the comfort of the passengers of the vehicle; and PA1 c) a good rigidity of the assembly of the slide because these slides cooperate for protecting the passengers in case of impacts or accidents; actually, in modern type vehicles, most of the seats are fitted with embarked safety belts, which means belts fixed to the considered seat and, therefore, the slides are subjected, in case of impacts or accidents, to very great tearing or twisting forces that they must absorb in order to avoid, the more as possible, more or less serious damages for the passengers. PA1 a) the inner profile member has a U-shaped cross-section extended by arcuate parts; PA1 b) the outer profile member comprises an upper plane portion edged in a symmetrical manner, with respect to a median vertical axis, by first guiding paths extended by connecting parts linking together these first guiding paths with second guiding paths, sliding or rolling members being inserted between the first guiding paths and the arcuate parts, then between these arcuate parts and the second guiding paths, these arcuate parts thereby permitting a slight relative rotation movement of the inner and outer profile members. PA1 a) the arcuate parts have a protruding portion limiting the respective rotation of the inner and outer profile members; PA1 b) the arcuate parts of the inner profile member are extended by turned down parts; PA1 c) the connecting parts surround the turned down parts; PA1 d) the sliding or rolling members are made by small balls; PA1 e) the inner and outer profile members are made of a slightly flexible and resilient special steel.
But a good rigidity is not compatible with a low sliding force and with the taking up of environmental defects. Actually, the presently used profile members are either sufficiently flexible for absorbing the defects, or they are rigid; but in this later case the defects are not absorbed and a clearance is necessary for permitting a low sliding force.